Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
  • B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
  • B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H47/00—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current
  • H01H47/002—Monitoring or fail-safe circuits
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H50/00—Details of electromagnetic relays
  • H01H50/14—Terminal arrangements
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
  • B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
  • B60L3/04—Cutting off the power supply under fault conditions
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
  • G01R1/20—Modifications of basic electric elements for use in electric measuring instruments; Structural combinations of such elements with such instruments
  • G01R1/203—Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
  • G01R19/0092—Measuring current only
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H50/00—Details of electromagnetic relays
  • H01H50/44—Magnetic coils or windings
  • H01H50/443—Connections to coils
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
  • H01H85/02—Details
  • H01H85/04—Fuses, i.e. expendable parts of the protective device, e.g. cartridges
  • H01H85/041—Fuses, i.e. expendable parts of the protective device, e.g. cartridges characterised by the type
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H1/00—Details of emergency protective circuit arrangements
  • H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/02—Details
  • H02H3/05—Details with means for increasing reliability, e.g. redundancy arrangements
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
  • H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for DC applications

Definitions

• a contactor is typically used to selectively connect and disconnect the battery to/from the electric motor or to/from the charging circuit under normal circumstances.
• the electrical power circuit may further comprise a fuse to open the circuit in case of an emergency, e.g. in case of a collision.
• the high-voltage domain and the low-voltage domain are galvanically separated. It is an advantage of using a magnetic sensor, preferably physically located in close vicinity of the electrical conductor portion but galvanically separated therefrom, in that it allows circuitry in the low-voltage domain to measure the current flowing in the high-voltage domain, namely, through the electrical conductor portion.
• the actuator comprises a coil and an element which is movable relative to said coil.
• the actuator may further comprise a spring biased for opening the switch (NO type) or biased for closing the switch (NC type).
• the controller is further configured for measuring a secondary current flowing through the coil; and the controller is further configured for determining the primary current based on the signal obtained from the magnetic sensor, and taking into account the secondary current.
• the signal obtained from the magnetic sensor itself may be corrected for a magnetic field generated by the coil at the position of the magnetic sensor, for example by subtracting the secondary current value multiplied by a predefined constant from the primary current value. In this way, the current flowing through the electrical conductor portion can be measured with improved accuracy, while at the same time allowing a compact design (the magnetic sensor and the coil may be relatively close together, and magnetic shielding is not absolutely required).
• the detection means comprises a shunt resistor configured for measuring a current flowing through the actuation means; and the controller is further configured for measuring a voltage over this shunt resistor in order to determine a current flowing through the shunt resistor and through the coil; and wherein the controller is further configured for repeatedly (e.g. periodically) sampling the current flowing through this shunt resistor thereby obtaining a current waveform, and for analysing this current waveform in order to detect a characteristic indicative of movement of the movable element.
• the detection means comprises a position sensor (e.g. a magnetic position sensor, e.g. based on the magnetic field emitted by a permanent magnet) for detecting a position of the movable element; and the controller is connected to said position sensor for determining the position of the movable element, thereby determining the status of the switch (i.e. open or closed).
• a position sensor e.g. a magnetic position sensor, e.g. based on the magnetic field emitted by a permanent magnet
• the magnetic sensor comprises at least one horizontal Hall element, or at least one vertical Hall element, or at least one magneto-resistive element, arranged in the vicinity of said electrical conductor portion, and configured for measuring a magnetic field component generated by the current flowing through said electrical conductor portion;
• the controller may determine the current flowing through the electrical conductor portion as being proportional to the measured magnetic field component.
• a magnetic shield may be provided in the vicinity of the magnetic sensor, in order to reduce the influence from an external disturbance field, or from the actuator coil.
• the magnetic sensor comprises at least two horizontal Hall elements or at least two vertical Hall elements, spaced apart from each other and oriented in parallel, and configured for measuring a magnetic field difference or a magnetic field gradient.
• the contactor further comprises an accelerometer and/or a gyroscope connected to the controller; and the controller is further adapted for determining an abnormal condition (e.g. a collision occurred, or a vehicle is oriented upside-down after falling from a bridge, or the like) based on signals obtained from said accelerometer and/or said gyroscope; and wherein the controller is further configured for autonomously opening the primary switch and/or to blow the fuse if an abnormal condition is detected, e.g. by analysing certain parameters (e.g. acceleration parameters or orientation parameters).
• an abnormal condition e.g. a collision occurred, or a vehicle is oriented upside-down after falling from a bridge, or the like
• the controller is further configured for autonomously opening the primary switch and/or to blow the fuse if an abnormal condition is detected, e.g. by analysing certain parameters (e.g. acceleration parameters or orientation parameters).
• the controller is implemented in an integrated semiconductor device; and the magnetic sensor is also integrated in said semiconductor device; (e.g. in the same packaged device, e.g. as a separate component on the lead frame, or integrated on the same silicon substrate as the controller); and wherein the actuator comprises a coil connected in series with a second switch; and wherein the detection means comprises a shunt resistor connected in series with said coil; and wherein the controller is configured for sampling a first voltage over said shunt resistor, and for sampling a second voltage over said coil or over the series connection of said coil and said shunt resistor, and for determining a status of the primary switch based on the first and second voltage samples; and wherein the controller has a first output for controlling the actuator for operating the primary switch; and wherein the controller has a second output for blowing the fuse.
• the controller may further comprise an analog-to-digital convertor (ADC), and a timer, and a clock circuit, and a non-volatile memory (e.g. flash), and a PWM-module, etc.
• ADC analog-to-digital convertor
• timer e.g. 1
• clock circuit e.g. 1
• non-volatile memory e.g. flash
• PWM-module e.g. flash
• the present invention also provides a power circuit, comprising: an electrical battery for providing electrical power; an electric load comprising an electrical motor; a contactor according to any of the previous claims, connected to said battery by means of its first power terminal, and connected to said electric load by means of its second power terminal, or vice versa.
• the electrical load may further comprise a three-phase convertor.
• the present invention also provides an electric or a hybrid vehicle, comprising a contactor according to the first aspect, or a power circuit according to the second aspect.
• the electrical vehicle may further comprise at least one airbag.
• the electrical vehicle may further comprise an Engine Control Unit (ECU), connected to the contactor via said communication port.
• the ECU may be configured to provide a signal to the contactor to open the switch based on a signal obtained from the airbag.
• the controller inside the contactor can determine whether the primary switch has actually opened or not, and thus can also detect that the switch did not open for whatever reason. This may happen for example in case the contacts of the switch are stuck or welded to the bus bar due to a current surge. In such a case, the controller will decide to blow the fuse to stop the current.
• the contactor is able to detect (itself) whether the switch is effectively open or closed using said detection means.
• the contactor is able to detect autonomously that the switch is open or closed, and without having to rely (or to rely solely) on the measurement from the magnetic sensor (which may be corrupt or damaged), and/or without having to communicate with an external device (which communication channel may be broken and/or cause a delay), and/or without having to use or rely on a component outside of the contactor.
• This provides redundancy (at system level) and thus improves overall safely and reliability of the electrical power system in which this contactor is used.
• the communication-loop or feedback-loop of certain events is shortened (as compared to a communication loop that involves one or more communication(s) with an external processor and/or components located outside of the contactor).
• This shortened loop in turn provides extra time during which an attempt can be made to open the switch without having to blow the fuse, which would damage the contactor in an irreversible way.
• the lifetime of the contactor may be increased by avoiding that the fuse is blown, e.g. in situations where the current is sufficiently small and/or there is sufficient time to safely open the switch.
• this contactor (under certain conditions), it can first try to open the switch in a reversible manner, which may not be possible if valuable time was lost due to communication with external devices.
• the probability of having to blow the fuse according to a safety criterion can be reduced.
• the "detection means” provides a way to analyse whether the switch is closed (which is a form of internal diagnostics) in a manner which is independent from the current measurement performed by the magnetic sensor.
• the reliability of the contactor can be increased, and safety of an electrical power system in which this contactor is used, can be improved.
• the lifetime of the contactor can be increased, because without the detection means, the only safe option would be to blow the fuse.
• the contactor of the present invention can make a better judgement to decide whether the current is small enough and/or there is sufficient time to try to open the switch, and if this succeeds, the fuse does not have to be blown.
• the fuse is also integrated in the contactor, because the housing of the contactor provides protection to the fuse and to the interconnection between the controller and the fuse. Thus, the risk that the fuse cannot be blown is reduced, and the safety of the overall system is further increased.
• the controller may further comprise at least one (e.g. one or two) communication interface (e.g. a unidirectional or bidirectional serial bus interface) which is connectable to an external processor (e.g. to an external ECU, e.g. to an airbag ECU and/or to a Battery Management System controller) for sending and receiving information or instructions, e.g. for providing a signal indicative of the measured current, and/or for receiving one of the following commands: a command to open the switch (or to disconnect the battery), a command to close the switch (or to connect the battery), a command to blow the fuse.
• an external processor e.g. to an external ECU, e.g. to an airbag ECU and/or to a Battery Management System controller
• information or instructions e.g. for providing a signal indicative of the measured current, and/or for receiving one of the following commands: a command to open the switch (or to disconnect the battery), a command to close the switch (or to connect the battery), a command to blow the fuse.
• the opening of the switch can be triggered by one or more of the following events: (a) the detection of an overcurrent condition by the contactor itself, for example by comparing the measurement current with a threshold value, or by using a classical I2T (ampere-squared time seconds) technique; or (b) the receipt of a command to disconnect the battery, or open the switch from an external processor, for example from an airbag controller.
• the contactor receives a command to unconditionally blow the fuse, or that the contactor reports an abnormal HV current, etc.
• the present invention also provides a method of interrupting a current flowing through such a contactor, comprising the method steps (i) to (iii) described above. This method will be described in more detail, when discussing FIG. 4 .
• FIG. 1 shows a high-level block-diagram of an electrical power circuit 100 comprising a battery 111 (e.g. a high-voltage battery providing a voltage of at least 100 Volt, or at least 200 V), connected to an electrical load 120 (e.g. an electrical two-phase motor or an electrical three-phase motor or a charging circuit) via a contactor 150.
• the electrical power circuit 100 may be incorporated in an electric vehicle (EV) or in a hybrid vehicle (HV), for example a car.
• the electrical power circuit 100 may comprise further components, such as e.g. an inverter (not shown).
• the contactor 150 of FIG. 1 comprises a first power terminal 151a which is connected or connectable to the battery 111, and a second power terminal 151b which is connected or connectable to the electrical load 120, but of course, the contactor 150 can also be used in other power circuits.
• the contactor 150 comprises a sub-circuit in electrical connection between the first power terminal 151a and the second power terminal 151b, and comprising at least the following three elements connected in series: an electrical conductor portion 154 (e.g. a busbar), a switch 153 (e.g. an electromagnetic switch), and a fuse 158 (e.g. a pyro-fuse) or a squib.
• the electrical conductor portion 154 may be formed integral with the first power terminal 151a or may be formed integral with the second power terminal 151b, but that is not absolutely required.
• the electrical path formed between the first and second terminal 151a, 151b is conductive, i.e. the battery is connected to the electrical load. If the switch 153 is open and/or the fuse 158 is blown, the electrical path formed between the first and second terminal 151a, 151b is open, or stated in other words: the battery is disconnected from the electrical load.
• the contactor 150 further comprises a controller 160, e.g. a programmable microcontroller, optionally with a non-volatile memory 161, a timer unit, a PWM-generator block, an analog-to-digital convertor (ADC), a communication interface (e.g. a serial communication interface, e.g. a CAN interface), a clock generator (e.g. crystal based or based on an RC oscillator), etc.
• the controller 160 is powered by a low supply voltage, e.g. a second battery, located outside of the contactor but connected thereto, and configured for providing a low voltage supply, e.g. of 48 Volt or less, or 36 Volt or less, or 24 Volt or less, e.g.
• the low voltage is applied to the contactor via low voltage terminals 152a, 152b.
• the controller may be powered by this low supply voltage directly, or by a voltage derived therefrom, e.g. provided by one or more voltage regulators 162, if present.
• the controller 160 and the voltage regulator(s) 162, if present, may be mounted on a printed circuit board (PCB, not shown).
• the controller 160 may be part of an integrated circuit. A preferred embodiment of such an integrated circuit will be shown in FIG. 5 .
• the contactor 150 further comprises a housing (not explicitly shown, but schematically indicated by the rectangle 150 with rounded corners). As illustrated, the switch 153 and the fuse 158 and the controller 160 are situated inside the housing. This reduces the risk that the fuse cannot be blown in case of an emergency, e.g. after a collision. Importantly, the switch 153 and the fuse 158 operate in the high voltage domain, whereas the controller 160 (and other components which will be described further) operate in the low voltage domain which is galvanically separated from the high-voltage domain.
• the contactor further comprises a magnetic sensor 155 configured for measuring (in a contactless manner) a current flowing through the electrical conductor portion 154.
• Magnetic current sensors are known in the art, and hence need not be explained in full detail here. Suffice it to say that they may comprise at least one magnetic sensor element, e.g. a horizontal Hall element, or a vertical Hall element oriented to measure the magnetic field created by the current when flowing through the electrical conductor portion 154, but other magnetic sensor structures may also be used, for example comprising a magneto-resistive (MR) element, or at least two Hall elements, spaced apart and oriented in a same direction, allowing to determine a magnetic field gradient. Using a difference signal or a gradient signal allows to determine the current flowing through the electrical conductor portion 154 with a reduced influence from an external disturbance field, thus with improved accuracy.
• the magnetic sensor may comprise a magnetic flux concentrator.
• the value obtained from the magnetic sensor element or from the magnetic sensor structure comprising that magnetic sensor element may be amplified (e.g. using a differential amplifier) and digitized (e.g. using an analog-to-digital convertor ADC embedded in the controller 160), in manners known in the art.
• the current values, or a subset of the current values may be transmitted via a communication bus, e.g. a CAN-interface, to an external processor, e.g. to an external ECU.
• the magnetic sensor 155 may be embedded in the same silicon substrate as the controller 160, or may be located outside of the controller 160, but electrically connected thereto. Preferably the distance between the magnetic sensor 155 and the electrical conductor portion 154 is relatively small (e.g. smaller than 10 mm), in order for the signal to be sufficiently large. In certain embodiments the contactor 150 may have a plurality of magnetic sensor elements located at several distances from the electrical conductor portion 154. This allows to measure the current with a higher signal-to-noise ratio (SNR).
• SNR signal-to-noise ratio
• the switch 153 comprises a movable part (not shown) driven by an actuator 156.
• the actuator 156 may be an electromagnetic actuator comprising a coil (schematically illustrated in FIG. 2 ) and a movable element arranged inside said coil (not shown).
• the actuator 156 may also comprise a mechanical spring (not shown) for biasing the switch 153 to a Normal Open (NO) condition or a Normal Closed (NC) condition.
• the movable element can for example be controlled by sending a secondary current (LV current) through the coil (as illustrated for example in FIG. 2 ).
• LV current secondary current
• the actuator 156 of the contactor 150 of the present invention contains detection means 157 capable of detecting (directly or indirectly) whether the switch 153 is actually open or closed.
• detection means 157 capable of detecting (directly or indirectly) whether the switch 153 is actually open or closed.
• the actuator 156 comprises a coil and a shunt resistor connected in series with the coil, and the voltage over the shunt resistor is measured, and the voltage over the coil is measured, and digitized, and the voltage signals are analysed (e.g. in software) in the controller 160.
• the actuator 156 comprises a coil and a magnetic positioning means, e.g.
• the proximity switch may comprise a transmitter coil (for transmitting an RF signal) and a receiver coil (for receiving said RF signal), and a so called “target” may be connected to the movable element, for modulating the received signal.
• the controller 160 may analyse the receiver signal to determine the position of the target and thus the condition of the switch 153.
• a major advantage of adding a detection means 157 inside the contactor 150 is that the controller 160 can use it as a feedback means to determine whether or not the switch 153 is actually open or closed ("closed loop control"), independent of the signal obtained from the magnetic sensor 155, and without having to rely on a signal obtained from an external processor. Since the detection means is also incorporated inside the housing, the risk of a malfunction e.g. due to a signal disturbance or a broken communication link is highly reduced.
• the detection means 157 described herein can also be used for a safety check (at system level), e.g. by testing whether the primary switch is stuck- open, or stuck-closed. This is possible even if two contactors according to the present invention are connected in series between a battery and an electrical load, and one of the primary switches thereof is open. Even in that case, it is possible to check whether the primary switch of the other contactor is open or closed, not by measuring the primary current (which is zero), but by using the detection means 157.
• the controller 160 also has an output port (e.g. OUT2 in FIG. 5 ) which can trigger the fuse 158, e.g. directly, or via an optional activation circuit 163.
• an output port e.g. OUT2 in FIG. 5
• the HV-battery 111 provides a voltage of at least 100 Volt
• the low voltage battery 140 provides a voltage of at most 48 Volt
• the external controller 130 e.g. ECU
• the controller 160 may provide a signal to the controller 160 of the contactor 150 to connect the HV battery, or to close the switch 153 (or the like).
• the controller 160 will operate the actuator 156 (e.g. by energizing a coil) in order to close the switch 153, thereby allowing primary current to flow through the electrical conductor portion 154.
• the controller 160 may first perform internal safety checks (e.g.
• the external processor 130 may request the contactor 150 to measure the (primary) current flowing through the electrical conductor portion 154.
• the controller 160 will obtain a signal (e.g. a voltage signal) from the magnetic sensor 155, and will convert it into a current signal in manners known per se in the art (e.g. by amplifying and digitizing and multiplying with a constant K).
• the constant K may be hardcoded, or may be determined during a calibration step, and subsequently stored in the non-volatile memory 161 of the contactor 150.
• the measured signal is also temperature corrected in known manners.
• the contactor may further comprise a temperature sensor, which may be arranged in the vicinity of the magnetic sensor. In the integrated circuit of FIG.
• the (optionally temperature corrected) current value may be transmitted via an output port or via a serial bus interface, e.g. a CAN bus to the external processor 130.
• the non-volatile memory 161 may be incorporated inside the controller 160, e.g. in the form of flash, or may be a separate component connected to the controller 160.
• the controller 160 of the contactor 150 is also configured for measuring the HV current autonomously (even without receiving a command from an external processor to do so), and for detecting an overcurrent condition itself and/or to perform internal diagnostics. This may be based on a simple comparison of the measured current with a predefined threshold value I1 (e.g. a parameter which is stored in a non-volatile memory 161, or may be based on a classical I2T (ampere squared time) technique, or a combination of both. This will be further discussed in relation to FIG. 3 . As explained above, if the controller has detected an overcurrent condition, it will first try to open the switch, and if the switch does not open, to blow the fuse, as described in steps (i) to (iii) above.
• I1 e.g. a parameter which is stored in a non-volatile memory 161
• I2T ampere squared time
• the external processor 130 may request the contactor 150 to disconnect from the HV battery (or to open the switch 153).
• a classical contactor would simply operate the actuator 156 so as to open the switch 153 (in an open-loop manner), but would not know if the switch is actually open.
• the external processor may request a new current measurement, and if the external processor notices that the current does not drop, may send a new request to the contactor to open the switch 153, which may fail again, until eventually the external processor would instruct another component to blow a fuse. This is not ideal, may require too much time, which in turn may lead to dangerous situations.
• the external processor 130 is an airbag ECU
• a collision occurs causing an airbag to be activated.
• the airbag ECU may send a command to unconditionally blow the fuse, as a safety precaution.
• the contactor 150 proposed herein will make sure that the HV current will be interrupted, but will only blow the fuse when absolutely required. More specifically, when the controller 160 receives a command from an external processor to "interrupt the current flow” (or to "disconnect the battery” or “to open the switch” or the like), it will first try to open the switch, and if the attempt fails or if there is insufficient time, it will autonomously blow the fuse. This will be explained in more detail when discussing the method of FIG. 4 .
• the contactor 150 may optionally further comprise a magnetic shielding for reducing a magnetic disturbance caused by the actuator coil (if present) on the magnetic sensor 155.
• the controller 160 and/or the printed circuit board on which it may be mounted is electrically isolated (galvanically separated) from the HV domain, in particular from the electrical conductor portion 154 (e.g. busbar portion), and is preferably also thermally isolated from the HV domain.
• the contactor may measure the HV current at a first, relatively high sampling rate (e.g. at a rate from 1 kHz to 10 kHz) for diagnostic purposes, and a subsampled version thereof may be provided to an external ECU, e.g. to a Battery Management System controller (e.g. at a rate from 100 Hz to 500 Hz).
• a first, relatively high sampling rate e.g. at a rate from 1 kHz to 10 kHz
• a subsampled version thereof may be provided to an external ECU, e.g. to a Battery Management System controller (e.g. at a rate from 100 Hz to 500 Hz).
• FIG. 2 shows a block-diagram of a contactor 250 and an electrical power circuit 200 comprising at least one such contactor, which can be regarded as a variant of, or a specific implementation of the contactor 150 and the electrical power circuit 100 of FIG. 1 .
• Like elements are indicated by like reference numerals.
• the main differences between the block-diagram of FIG. 2 and that of FIG. 1 are the following:
• the controller 260 may be mounted on a printed circuit board (not shown), which PCB is mounted inside the contactor 250, and is electrically and preferably also thermally isolated from the HV domain.
• the electric power circuit has at least two contactors, for example two contactors connected in series or two contactors connected in parallel, or one contactor in the path from the battery to the load, and another contactor in the return-path from the load to the battery.
• FIG. 3 shows an exemplary "time-current curve" which can be used in embodiments of the present invention, for example in order to determine how much time ⁇ tav is available to try to open the switch 153, 253 as a function of the measured HV current flowing through the electrical conductor portion 154, 254.
• a graph may be specific for a particular vehicle type, may depend on busbar network dimensions, thermal limitation of the powertrain modules, etc. The graph may be considered as a given for a particular project. Values of this graph may be stored in the non-volatile memory of the controller in any suitable manner (e.g. as a table, or as a piece-wise linear curve, or as a set of parameters of an algebraic expression, or in any other suitable way).
• the controller 160, 260 of the contactor 150, 250 can measure the HV current flowing through the electrical conductor portion 154, 254 upon request, or autonomously.
• it typically takes a finite amount of time ⁇ treq (required time) to open the switch under normal circumstances, (i.e. assuming that the movable part is not stuck), say for example about 90 ms for a particular type of switch.
• the controller measures the HV current, and if this measured current is larger than the value Imax (see FIG. 3 ), then the controller knows that there is no time to even try to open the switch, and hence the controller will immediately blow the fuse. If the measured current is smaller than Imax, a maximum time that this current is allowed to flow is shown by this graph. For example if the measured current is equal to i1, the maximum time is t1. If the maximum allowed time is smaller than the time typically required for opening the switch, or for performing safety checks and opening the switch, (depending on the implementation), (e.g. the above mentioned 90 ms), then again, it is not worth to even try to open the switch, and the controller will immediately blow the fuse.
• the controller of the present invention is capable of guaranteeing safety, while at the same time maximizing the lifetime of the contactor.
• FIG. 4(a) shows a flow-chart of a method 400 of interrupting a current flowing through a contactor 150, 250 like the one shown in FIG. 1 or FIG. 2 .
• the method 400 comprises the following steps:
• step 403 determining an overcurrent condition
• the controller performs step 403 (determining an overcurrent condition), because this may automatically trigger the opening of the switch and/or the blowing of the fuse sooner, (e.g. before an external processor has detected that something is wrong), thereby avoiding or reducing the risk to damage the vehicle and/or endangethe life of its occupants.
• a faster detection also increases the probability to keep the fuse alive.
• the method 400 describes a relative simple procedure, and shows the most important steps proposed by the present invention. But many variants of this method are possible.
• step c) and d) are omitted, and the branch to blow the fused is omitted, and the time-out value of step 410 is predefined (e.g. hardcoded).
• the contactor would measure the current in step a), and in case an overcurrent is detected in step b), the contactor will first try to open the primary switch in steps e) and f), and will evaluate if the primary switch is actually open after said predefined time-out period. And in case the primary switch is not open, the contactor will blow the fuse.
• FIG. 4(b) shows a flow chart of a method 410 which is a further variant of the one described here above, wherein, after detecting that an overcurrent condition has occurred (or as part thereof), the contactor would test (in step 414) if the measured primary current is larger than a predefined (critical) threshold value, and if that is the case, the contactor will blow the fuse (in step g). Otherwise, the contactor will first try to open the primary switch in steps e) and f), and will evaluate if the primary switch is actually open after a predefined time-out period ⁇ T (in step 410). And in case the primary switch is not open, the contactor will blow the fuse (in step g).
• FIG. 4(c) shows a flow-chart of a method 420 of interrupting a current flowing through a contactor 150, 250, which can be seen as another variant of the method 400 of FIG. 4(a) .
• the most important difference between the method 420 of FIG. 4(c) and the method 400 of FIG. 4(a) is that it contains a step 413 in which it is tested whether the time lapsed since the overcurrent situation was detected in step b) is larger than the available time ⁇ tav, and if that is not the case, to go back to step c) and update the available time ⁇ tav.
• the available time ⁇ tav is updated at least once, e.g. is dynamically updated, taking into account recent measurements of the primary current (in step a), thus effectively taking into account variations of the primary current while trying to open the switch.
• FIG. 4(d) shows a flow-chart of a method 430 of interrupting a current flowing through a contactor 150, 250, which can be seen as another variant of the method 400 of FIG. 4(a) .
• the most important differences between the method 430 of FIG. 4(d) and the method 400 of FIG. 4(a) are:
• the steps 401, 403, 405 and/or 402 may be performed in parallel, or semi-parallel, e.g. in a time-multiplexed manner.
• FIG. 4(a) to FIG. 4(d) show four examples of methods which may be performed by the controller of the contactor proposed herein, but of course, in practice, other variants are also possible.
• testing or evaluating or assessing 409 whether the primary switch 153, 253 is actually open can be performed indirectly, by evaluating the state of the actuator.
• the state of the actuator can for example be determined by measuring and analysing a current waveform of the actuator (e.g. using a shunt resistor) to detect whether the movable element has actually moved or not.
• the state of the actuator can also be determined by using a position sensor (e.g. a magnetic position sensor, or a proximity sensor), or in any other suitable way.
• Step 409 of "detecting whether the switch is open may comprise measuring the voltage over the shunt resistor and/or the voltage over the coil (or the coil in series with the switch, or the coil in series with the shunt), and may thus involve multiple voltage measurements. These two voltages may be measured and sampled using a time-multiplexing scheme, and a single or two analog-to-digital convertor (ADC).
• ADC analog-to-digital convertor
• controller 160, 260 of the contactor 150, 250 may also perform other tasks (not shown in FIG. 4(a) to FIG. 4(d) , such as for example:
• FIG. 5 shows a block-diagram of an integrated circuit 500 as can be used in embodiments of the present invention.
• the integrated circuit 500 of FIG. 5 comprises:
• the non-volatile memory may also contain data corresponding to a current versus time curve.
• the "shunt interface”, and the "voltage sensing interface” and the “supply voltage interface” are shown with 6 terminals (or pins), but that is not absolutely required, since some signals can be shared with the "ground terminal”, in manners known in the art.
• the integrated circuit 500 may further comprise one or more of the following: a clock generator (e.g. crystal based or based on an RC oscillator); a voltage-regulator; a timer unit; an analog multiplexer; a pulse-width modulation (PWM) generator block, e.g.
• a clock generator e.g. crystal based or based on an RC oscillator
• a voltage-regulator e.g. crystal based or based on an RC oscillator
• a timer unit e.g., a timer unit
• an analog multiplexer e.g.
• PWM pulse-width modulation
• a digital communication interface for receiving instructions from an external processor; an analog-to-digital converter (ADC) for digitizing a signal obtained from the shunt interface, and configured for digitizing a signal obtained from the voltage sensing interface; a 12 Volt supply input; a timer unit; an NTC interface (Negative Temperature Coefficient component) to measure an external temperature; a temperature sensor for measuring or estimating a temperature of the magnetic sensor.
• ADC analog-to-digital converter
• FIG. 6 shows a block-diagram of an integrated circuit 600 which can be seen as a variant of the integrated circuit 500 of FIG. 5 , with a coil interface circuit comprising an integrated shunt resistor, and an integrated transistor for controlling current flow through the coil.

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